1. Field of the Invention
The present invention relates to a method for manufacturing a thermosetting FRP (fiber reinforced plastic).
2. Description of the Related Art
Heretofore, there has been known a method for manufacturing a composite material by laminating a number of FRP (fiber reinforced plastic) sheets which are impregnated with thermosetting adhesive resin, which are so-called prepregs, and subjecting the same to hot press treatment to manufacture the composite.
The composite is formed, for example, as a long channel member, and cut to necessary lengths for use. The composite channel member is light weight and has high strength, and the channel members are often bonded to other panel members etc. to form a structure.
FIG. 6 is an explanatory view showing a common hot press treatment for thermosetting FRP.
As illustrated in FIG. 5, an FRP sheet 1 used as the material is a woven sheet 1 formed by weaving a weft 10 and a warp 20 of FRP fiber in a plain weave style, as shown in FIG. 5(a), or by weaving the weft 10 and warp 20 respectively tilted for 45 degrees in a 45-degree plain weave style, as shown in FIG. 5(b).
The woven sheet 1 has a gap 30 formed at a crossing section between the weft 10 and the warp 20, and in the gap 30 is impregnated the thermosetting resin, thereby obtaining the prepreg sheet 2.
As shown in FIG. 7, release films 50 and 60 are disposed on the upper and lower surfaces of the prepreg sheet 2, and then as shown in FIG. 8, the prepreg sheet is sandwiched between an upper mold 70 and a lower mold 80 of a hot press to be subjected to heating and pressurizing for a given period of time.
The selected thermosetting resin 40 has a curing temperature of 120 to 130° C.
The release films 50 and 60 are for preventing the thermosetting resin 40 oozing out of the prepreg sheet 2 from adhering to the surface of the press molds 70 and 80. The softening temperature of the release films is selected to be higher than the curing temperature of the thermosetting resin, or approximately 260° C.
When the hot press treatment is completed, the release films are peeled off and a product 3 is obtained. Surfaces 3a and 3b of the product 3 are smooth.
FIG. 9 shows a channel member manufactured according to the above-mentioned method. The channel member has an angulated U-shaped cross-section with three faces 3a, 3b and 3c. 
In many cases, these types of channel members are bonded to other sheet members or panel members to constitute a structure. In such use, the channel member should preferably have fine uneven patterns formed to the surface thereof to enhance adhesiveness.
One process for providing uneven patterns on the surface of a resin member is known as surface texturing (embossing).
Japanese Patent Application Laid-Open Publication No. 06-122143 discloses such surface texturing process.
According to the art disclosed in the above-mentioned patent document, surface texturing is provided to the surface of a molded product by use of a transfer film having a surface texturing pattern formed thereon.